Mine firing control device



Nov. 8, 1960 c. M. VAN ATTA ETAL 2,959,125

MINE FIRING CONTROL DEVICE 4 Sheets-Sheet 1 Filed Feb. 18, 1942 S n TAH N mTl VHN n m w A ,NO AR VB MW.. QF.

Nov. 8, 1950 c. M. VAN ATTA ETAL 2,959,125

MINE FIRING CONTROL DEVICE Filed Feb. 18, 1942 l 4 sheets-sheet 2 0 2.27.5 55 Q es o fsf JL es eo f 0 S I., 5|

53 TD2 O sM o 0 G se TD 2 ff*- sl 59 C) 59 lNvENoRs L f J c.M.vAN ATTA 68 67 F. w. aRowN m BY ATT NEY Nov. 8, 1960 c. M. VAN ATTA E'rAL 2,959,125

MINE Emme CONTROL DEVICE Filed Feb. 1s, 1942 4 sheets-sheet s C.M.VAN ATTA F. W. BROWN IH ATT NEY INVENTORS Nov. 8, 1960 Filed Feb C. M. VAN,ATTA ETAL MINE FIRING CONTROL DEVICE FIRING CONTACTS conTAcr 78 -r o e .CONTACT 76 can -rAer 77 5H 4 MAGNET I* 'l GYCLE Pl 4 Sheets-Sheet 4 l l l I l l l g "`r l l l ,'-A I i l II u .Y a I l INVENTORS G. M. VAN ATTA EW. BROWN Ill ATTO NEY nited States atent z,9s'9,12s

MINE rlnmo CONTROL DEVICE Chester M. Van Atta, Washington, D.C., and Frank W.

Brown III, Rome, N.Y. (both Navy Yard, Washington, D.C.)

Filed Feb. 18, 1942, Ser. No. 431,324

13 Claims. (Cl. 102-18) (Granted under Title 35, U.S. Code (1952), sec. 266) This invention relates to devices for controlling Ithe firing of a submarine mine selectively in accordance with signals corresponding to a predetermined number of changes in the magnetic field adjacent thereto in which the mine is unresponsive to additional signals for a predetermined period of time after the first signal has been received. More specifically the invention relates to a mine ring control system and devices therefor in which a pivoted magnetic needle or bar is employed to detect changes in the magnetic field and close an electrical circuit to certain selecting and time delay devices whereby a detonating device is brought under the control of the magnetized element after a certain number of changes of the magnetic field have been received in predetermined time relation in accordance with a predetermined setting of the device.

It is the general practice in the systems employed with influence type mines such, for example, as mines controlled by variations in the magnetic field adjacent thereto, to employ various devices adapted to prevent the premature detonation of the mines by mine-sweeping operations. In the case of magnetic influence mines the mine sweeping operations employed usually are controlled from a vessel, hereinafter referred to as a mine sweeper, having a wire trailing therefrom insulated from the sea water except at the furthermost end thereof in which a strong current is applied to the wire periodically thereby setting up an electromagnetic eld about the wire of sutlicient strength to actuate the magnetized bar and firing contacts associated therewith to the firing position, such an operation being referred to here-in as a mine sweeping operation. The current is applied to the sweep wire usually for relatively short periods of time thereby'to conserve the electrical energy required for setting up the electromagnetic field, it usually being suflicient to apply the current to the sweep wire for periods of one or two seconds to cause the tiring contacts of an influence type mine within the vicinity of the sweep wire to be moved toclosed position. Various arrangements and systems have heretofore been proposedV for rendering magnetic influence mines difficult to detonate by mine sweeping operations, such devices usually requiring rather delicate adjustments and complicated circuitA arrangements therefor.

The system of the present invention possesses all of the advantages of the prior devices and the additional advantage of simplicity of construction, inexpensiveness of manufacture, ruggedness and reliability in operation. The present system comprises timing mechanisms or relays adapted to control the selective operation o f an electro-responsive stepping switch mechanism having a plurality of terminal connections thereon correspondi-ng respectively to a plurality of different settable positions and a selecting switch device operatively connected to the terminals of the electro-responsive switch whereby the switch is required to make a predetermined number of steps corresponding to `a predetermined position ai Patented Nov. 8, 1960 or setting of the station selection device. When this occurs a circuit is closed to a detonating device thereby causing the mine to be exploded. The mine is provided preferably with hydrostatic devices adapted to set a starting clock in operation when the mine has been submerged a sufficient depth within a body of water thereby to connect the mine firing contacts and selection control mechanism to a source of electrical energy when a predetermined period of time has elapsed following the launching of the mine. The number of operations of the firing contacts in predetermined time relation necessary to explode the mine are controlled by a selection switch settable at will to a predetermined setting prior to the launching of the mine within the body of water.

One of the objects of the present invention is the provisi-on of new and improved means for controlling the firing of a submarine mine selectively in accordance with a predetermined number of firing impulses received corresponding respectively to one of the natural phenomena produced by a vessel within the vicinity of the mine.

Another of the objects is the provision of new and improved means for selectively controlling the tiring of a submarine mine in which the possibility of premature detonation of the mine by countermine operations is prevented.

Another object is the provision of new and improved means for controlling the firing of a submarine mine selectively in response to a number o-f changes in the magnetic field adjacent thereto and for causing the field detecting means to be ineffective for a period of time irnrnediately following a change in the magnetic field.

Still another object is the provision of new and improved means for controlling the firing of a submarine min-e selectively in accordance with a plurality of tiring impulses of predetermined character received in time spaced relation corresponding to predetermined intervals o-f time. n

Still other objects, advantages and improvements will be apparent from the following description taken in connection with the accompanying drawings of which:

Fig. l is a View in section of a submarine mine in which the system of the present invention is employed;

Fig. 2 is a plan view partly broken away of the mine of Fig. 1;

Fig. 3 is a view in elevation of a preferred form of electro-responsive switching mechanism suitable for use with the present invention;

Fig. 4 is a plan View of the device of Fig. 3;

Fig. 5 is a view in elevation of the reverse side of the device of Fig. 3;

Fig. 6 is a view of a settable switch device suitable for controlling the number of operations of the device o Fig. 5 required to tire the mine;

Fig. 8 shows in diagrammatic form the operation of the system of Fig. 7.

Referring now to the drawings on which like numerals of reference are employed to designate like parts throughout the several views, and more particularly to Fig. 1 thereof, there is shown thereon a submarine mine comprising a casing 11 having a recessed portion 12 therein within which is disposed a member 13 having an aperture therein for slideably supporting the shaft or plunger 14. The plunger is provided preferably with an expanded end 15 maintained in continuous engagement with a flexible diaphragm 16 as by the retractile spring 17 disposed about the shaft. The flexible diaphragm, it will be understood, is clamped to themember 13 as by the bolts 18 and the clamping ring 19 whereby the seepage or leakage of water within the mine is prevented. The recessed portion 12 is continued to form a chamberv 10 Within which 'is disposed a booster charge 20 adapted to be 'exploded by a detonating device 21'aixed in any suitable manner to the plunger 14 and adapted to be inserted within the booster charge-in response to the operation of the hydrostat as the'fiexible diaphragm 16 thereof 'is moved inward by the 'pressure of the Water within which the mine is submerged. A suitable bracing member 22 may be provided, if desired, between the chamber and the casing 11 of the mine.

There is also provided within the casing 11 a recessed portion 23 having an insert or supporting member 24 secured thereto within which is slideably supported a plunger 2S provided with an expanded or extending end 26 continuously maintained in contact with the flexible diaphragm 27 as by the retractile spring 28. A starting clock 29 of any type suitable for the purpose such, for example, as the starting clock disclosed in the copending application of James B. Glennon and Chester M. Van Atta, Serial No. 395,230, filed May 26, 1941, now Patent No. 2,905,088, for improvements in Firing Mechanism for a Submarine Mine, is secured to the supporting member 24 in any suitable manner and adapted to be set in operation as the plunger 25 is moved inward by the pressure of the water on the flexible diaphragm 27.

There is also provided within the mine a chamber 30 within which is disposed an electro-responsive stepping switch device 32'adapted to be set successively to different settings in accordance with the changes in the magnetic field adjacent the mine and having a clock timing or delay device 40 preferably secured there-to. The mine is also provided with a shelf or partition 33 upon which is disposed a manual type selecting switch or station selector 34 adapted to be set to different positions corresponding to the number of operations of the stepping switch 32 required to operate the detonator 21 and fire the mine. Secured to a partition 35 in any suitable manner is another timing device indicated generally by the numeral 36, the timing devices 36 and 40 being hereinafter referred to as TD1 and TD2 respectively.

There is also provided a mine firing mechanism 37 such, for example, as the type disclosed in the copending application of James B. Glennon and Chester M. Van Atta, Serial No. 395,230, filed May 26, 1941, now Patent No. 2,905,088, hereinbefore referred to, in which a pivoted magnetic needle or bar is caused to rotate about a horizontal axis in response to a change in the vertical component of the magnetic field and thereby close a pair of ring contacts, a suitable resilient pad or cushion 38 being provided for yieldably supporting the mine firing mechanism within the casing of the mine thereby to prevent injury to the mine firing mechanism during the handling, transportation or planting of the mine. An end cap or cover 39 is secured to the casing 11 as by the bolts 41, a suitable gasket 42 being provided therebetween to prevent the seepage of the water within the mine.

There is preferably arranged on the shelf 33 of the mine a terminal or junction box 42 having a plurality of cables extending therefrom to the firing control mechanism 37, the timing control clock mechanism 36, the starting clock 29, the electro-responsive stepping device 32, the timing mechanism 40, and the detonator 21, a tube or duct 43 being provided between the chambers 30 and 10 to facilitate an electrical connection to the detonator. The selection switch 34 is connected -to the terminals of the stepping switch 32 as by the conductors disposed within a cable 44 extending therebetween. There is also provided a battery BA arranged within the charnber 45 and insulated therefrom as by a exible rubber cushion or pad 50 thereby to prevent injury to the battery as the mine is launched, the battery being in electrical connection with the terminal box 42 as by the cable 70 extending therebetween. The mine is, of course, iilled with an explosive charge 47 adlPiCl 'E0 b? s?? Q by th? booster charge 20 in response to the operation of the detonator 21.

On Figs. 3, 4 and 5 is shown a well known type of stepping switch mechanism 32 having a pair of switch wipers 48 thereon rotatably mounted as at 49 and adapted to be moved into electrical engagement with the terminals 51 in succession as the switch arms are moved by the armature 52 and pawl 53 thereof in response to the operation of the stepping magnet SM. The wiper arms 48 are retained in any of the moved positions by a latch mechanism 54 adapted to be actuated by the operation of the release magnet RM whereby the arms 48 are 'restored by the retractile spring 55 to the initial or home position as illustrated on Fig. 5 with the stop member 56 secured thereto in engagement with the stop member 57 afxed to the frame of the switch. The switch is supported preferably by a mounting plate 58 by means of the resilient supports 59 and mounting screws 61 passing therethrough. The plate 58 is provided with a bushing 62 of suitable insulating material such, for example, as battente, hard rubber, tber and the like within which are disposed the electrical conductors 63. The switch terminals 51 are connected to the selection switch of Fig. 6 as by the conductors 64 passing through a suitable insulating bushing 65 Within the mounting plate 58.

Secured preferably to the electro-responsive stepping switch in any suitable manner as by the screws 66 is a relay clock mechanism TD2 having a plurality of electrical conductors 67 connected thereto passing through a suitable insulating bushing 68 within the mounting plate. There is also secured to the selecting switch a slow acting fuse 69 connected in series with the winding of the ro lease magnet RM and adapted to operate the release magnet for a period of time sufficient to insure the return of the switch wipers 48 to the initial or home -position before the fuse operates in response to the launching of the mine in the event that the wipers should have been previously moved therefrom.

On Fig. 6 is shown a selection switch SS settable at will to an initial or home position and to ten different moved positions, the switch having a plurality of terminals 71 thereon respectively associated with the different positions or settings of the switch and an additional terminal 72 adapted to establish an external electrical circuit with the switch wiper. The switch is also provided With a dial plate or cover 73 having a plurality of indicia thereon corresponding respectively to the different settings of the switch and arranged arcuately such that pointer 74 may be set to any desired position, an indicating `line 75 preferably being employed in connection with the foregoing indicia to give a visual indication of the setting of the switch whereby the firing control mecha-1 nism may be set to fire the mine in response to a pre determined number of signal indications received.

The operation of the system will best be understood from a consideration of Figs. 7 and 8 on which is shown in diagrammatic form the complete mine firing and selective control system therefor, and the operation of the system during one cycle of operations thereof respectively. The mine ring mechanism 37, Fig. 7, as heretofore stated, may be of any type suitable for the purpose such, for example, as the type disclosed in the copending application of James B. Glennon and Chester M. Van Atta, Serial No. 395,230 filed May 26, 1941, now Patent No. 2,905,088 heretofore referred to, the mine firing mechanism comprising, among other elements, a magnetized bar or needle 86 supported by a shaft 87 pivotally mounted for rotation about a horizontal axis and having a retractile or biasing spring 88 secured thereto adapted to set the magnetized needle at a predetermined setting such that a pair of tiring contacts FC are in open position re gardless of the latitude of the location within which the mine is arranged. Disposed adjacent each end of the magnetized needle respectively are a pair of air coreicoils HO and RS for maintaining the magnetized needle and firing contacts in the closed or tiring position and in a 'released position respectively as the respective coils are energized.

There is also included within the ring mechanism a pendulum 89 having a contact 91 thereon adapted to be normally disengaged from an annular contact member 92 and disposed coaxially therewith when the pendulum is in a vertical position, the pendulum being preferably supported by gimbals whereby the pendulum is caused to assume a vertical position regardless of the position of the mine on the bed of the body of water within which the mine is launched. A slow releasing relay R having one end of the winding thereof in electrical connection with the annular contact member 92 is also included in the mine firing mechanism 37. The operation of the pendulum 89 in response to an impulse of hydrostatic pressure or shock such, for example, as may be received as the result of a countermining operation causes the contacts 91 and 92 to be moved into engagement with each other thereby operating the release relay R and interrupting the circuit to the tiring contacts at the break contact thereof and establishing a circuit to the restore coil RS by reason of he closure of a pair of normally open cont-acts as the relay R operates. The relay R is provided with a copper slug disposed about the core of the relay coil, or otherwise prevented from releasing immediately in response to the interruption of the operate circuit thereto as the pendulum contacts are moved to the open position during the oscillation of the pendulum, whereby the release of the relay is delayed for a period of time suicient to prevent the premature detonation of the mine as the result of countermining operations.

The clock mechanism TD1 is provided with an electromagnet adapted to attract an armature in response to the energization of the electromagnet thereby to actuate a gear train having a cam element thereon adapted to close a pair of normally open contacts with a suitable time delay such, for example, as 21/2 seconds after the operate circuit to the winding of the electromagnet has been closed. When the operate circuit to the electromagnet is interrupted a retra-ctile spring causes the armature thereof to be restored to an initial or starting position.

There is also provided a clock or timing mechanism TD2 generally similar to the timing mechanism TD1 having the electromagnet thereof controlled by the contacts of the time delay clock mechanism TD1. When the electromagnet of the timing device TD2 is energized, the armature is attracted thereto thereby causing an escapement mechanism to operate continuously for a predetermined period of time such, for example, as 70` seconds.

There is provided on the timing mechanism TD2 a pair of normally closed contacts 76 adapted to be disengaged las the armature of the timing device TD2 moves away from the initial or home position thereof and remain disengaged until the armature is restored to the home position. There is also provided on the clock device TD2 a pair of normally open contacts 77 adapted to be engaged immediately or shortly after the contacts 76 are disengaged and adapted to be maintained engaged until a period of time such as 70 seconds has elapsed, the contacts 77 being disengaged during the return of the timing device TD2 to the original or home position thereof.

The electro-responsive selector switch comprises, among other elements, two levels or switch banks A and B having ten terminals thereon adapted to be engaged respectively by the switch wipers 1 and 2 in succession as the switch moves into the different settings thereof. Terminal 1 of level A is connected to terminal 2 of level B and to contact 1 of the manual switch SS. Terminal 2 of level A is connected to terminal 3 of level B and to contact 2 of the switch SS. In a similar manner terminals 3 to 9 of level A are connected to terminals 4 to 10 of level B and contacts 3 to 9 of the switch SS respectively. Contact of level A is connected to the detonator 21 and contact 10 of switch SS is preferably un-1 connected.

The operation of the system will now be described. Let it be assumed, by way of example, that the selector switch SS is set to position 2 and that the mine has been launched within a body of Water of a depth suflicient to cause the starting clock 29, Fig. 1 to be set in operation by the pressure of the water against the flexible diaphragm 27 of the clock hydrostat, that the detonator 21 has been inserted within the booster charge by the operation of the flexible diaphragm 16 and that a suflicient time has elapsed for the starting clock to connect the firing mechanism and control ci-rcuits thereof to the battery BA, this connection being indicated generally by the contacts 93, Fig. 7. Furthermore, let it be assumed that sufcient additional time has elapsed for the magnetized needle or bar 86 to assume a position such that the ring contacts FC thereof are disengaged from each other, the magnetized bar being held yieldably in the set position by the exible spring member 88 operatively connected thereto.

Let it be assumed, for the purpose of description, that the magnetized bar 86 is moved to the tiring position by `a change in the magnetic field adjacent the ymine such, for example, as may result from a mine sweeping operation. When this occurs the tiring contacts FC are brought into engagement with each other thereby closing a circuit from the positive terminal of battery BA, conductor 94, tiring contacts FC, biasing spring 88, conductor 95, winding of the hold-on coil HO, armature 96 and break contact of relay R, conductor 97, contacts 76 of the timing mechanism TD2, conductor 98, winding of the electromagnet of clock TD1, conductor 99, contacts 93 and thence to the negative terminal of battery BA thereby causing the clock TD1 to operate and move the contacts 78 thereof into engagement with each other after a delay of 21/2 seconds as contacts FC are engaged. A circuit is closed from the positive terminal of battery BA by way of conductor 94, winding of the electromagnet of clock mechanism TD2, conductor 101, contacts 78 of clock TD1, conductor 99, contacts 93 and thence to the negative terminal of battery BA thereby causing the electromagnet of clock TD2 to be energized and set the escapement mechanism thereof in operation as the armature is attracted by the electromagnet.

As the armature of clock TD2 moves away from its home or rest position the contacts 76 thereof are disengaged thereby interrupting the circuit to the electromagnet of clock TD1 and causing the armature thereof to be restored to its initial or starting position and contact 78 to be disengaged.

As the armature of time delay relay TD2 moves away from its initial or rest position, contacts 77 thereof are closed thereby completing a circuit from positive terminal of battery BA, conductor 94, the winding of magnet SM of the stepping switch mechanism, conductor 102, contacts 77 of clock mechanism TD2, conductor 99, contacts 93 and thence to the negative terminal of battery BA thereby causing the stepping magnet SM to be energized and attract the armature 52 thereof, Fig. 5, to the operated position and move the switch wipers 1 and 2 into engagement with terminal 1 of the switch banks A and B respectively. The time delay clock mechanism TD2, it will be recalled, is arranged to actuate the escapement mechanism thereof during the release stroke of the armature as the electromagnet thereof is deenergized by reason of the arrangement of the pawl and ratchet mechanism provided, the armature moving quickly to the operated position thereof in response to the energization of the electromagnet of the clock TD2. Furthermore, during the movement of the armature to the operate position thereof contacts 76 are disengaged and contacts 77 brought into engagement with each other as the armature moves away from its initial or rest position. As contacts 78 of the clock TD1 are disengaged, the

operate circuit to the electromagnet of clock TD2 -is interrupted thereby deenergizing the electromagnet and setting the escapement mechanism of the clock TD2 in operation.

The escapement mechanism operates for a period of time such, for example, as substantially 70 seconds before contact 77 is disengaged and the armature of the timing clock TD2 is restored to its initial or starting position. The disengagement of contacts 77 interrupts the flow of current through the stepping magnet SM of the selector switch mechanism thereby deenergizing the stepping magnet and causing the armature 52 thereof to be restored to the unoperated position by the restoring spring 60 secured thereto, Fig. 5. As the armature of the timing clock TD2 moves into the initial or starting position thereof contacts 76 are closed thereby bringing the clock timing device TD1 again under the control of the firing contacts FC. A cycle of operations has now been completed and the wipers of the electro-responsive switch are resting on their respective terminals 1.

During the foregoing cycle of operations it will be understood that the electromagnetic field set up by the current flowing through the sweep wire has decayed or collapsed and that the magnetized bar 86 and firing contacts FC are moved to open position as shown on Fig. 7 or moved suflciently to cause the tiring contacts to be disengaged following the deenergization of the hold-on coil HO as contact '76 of the timing clock TD2 is disengaged whereby the subsequent closure of contact 76 at the completion of the cycle of operations hereinbefore referred to completes a circuit adapted to maintain the firing contacts in the closed or firing positon thereof in response to a subsequent change in the magnetic field adjacent thereto.

Let it be assumed that the mine now receives a shock or pressure impulse such, for example, as may occur as the result of a countermining operation or that the mine is otherwise disturbed sufficiently to cause the pendulum 89 thereof to operate. When this occurs a circuit is closed from positive terminal of battery BA by way of conductor 94, contacts 91 and 92 of the pendulum 89, conductor 103, winding of relay R, conductor 99, contacts 93 and thence to the negative terminal of battery BA thereby causing relay R to operate. As armature 96 of relay R moves away from the break contact thereof the circuit to the winding of the hold-on coil HO is interrupted and, as armature 104 of relay R engages its make contact in response to the operation of the relay, a circuit is closed from the positive terminal of battery BA by way of conductor 94, winding of the reset coil RS, conductor 105, armature 104 and make contact of relay R, conductor 99, contacts 93 and thence to the negative terminal of battery BA thereby energizing the reset coil RS and setting up an electromagnetic field adjacent the magnetized bar 86 in a direction to maintain the firing contacts disengaged from each other regardless of the severity of the shock of pressure impulse received by the mine.

Relay R, it will be recalled, is a slow releasing relay and for this reason the armatures 96 and 104 thereof do not return to their unoperated position until a predetermined period of time has elapsed after the contacts 91 and 92 of the pendulum have been disengaged from each other. An arrangement is thus provided in which relay R is prevented from releasing during the period of time that the contacts 91 and 92 may be interrupted as the result of vibrations or oscillations of the pendulum 89. When the oscillatory movement of the pendulum has subsided sufficiently to maintain the contacts 91 and 92 in continuous disengagement from each other, the armatures 96 and 104 of relay R are restored to their unoperated condition, after a suitable time delay, thereby again bringing the clock mechanisms TD1 and TD2 under the control of thefiring contacts FC and interrupt- 8 ing the energizing circuit of the restore coil RS. The operation of relay R in response to a disturbance of the mine thus prevents the movement of the tiring contacts to the closed position thereof while the mine is in a disturbed condition and 'at the armature 96 and break contact of relay R interrupts the operating circuit to the time delay device TD1 whereby the possibility of operating the stepping magnet SM and advancing the switch wipers thereof to the firing position in response to a countermining operation is prevented.

As a vessel approaches within the vicinity of the mine, the ring contacts FC are moved into engagement with each other thereby closing a circuit from battery BA to the winding of the electromagnet of the clock TD1, the circuit including the hold-on coil HO and the contacts 76 of the time delay clock TD2. The clock TD1, it will be recalled, is arranged to operate the escapement mechanism thereof while the armature is being attracted toward the electromagnet. In the absence of a countermine operation Sufcient to cause the operation of relay R at this time, the energization of the hold-on coil HO maintatins the firing contacts FC in continuous engagement with each other thereby maintaining a continuous flow of current through the electromagnet of the timing clock TD1 for a period of -time sufficient to cause the contacts 78 thereof to be moved into engagement with each other after a delay of substantially 21/2 seconds. When this occurs the electromagnet of the clock TD2 is energized thereby quickly moving lthe armature thereof to the operated position and causing contact 76 to be disengaged and contact 77 to be closed. The disengagement of contact 76 interrupts the circuit to the electromagnet of the timing mechanism TD1 thereby causing contact 78 thereof to be disengaged and deenergize the electromagnet of clock TD2. The closure of contact 77 causes the stepping magnet SM to operate and advance the switch wipers into engagement with terminal 2 of their respective switch banks.

As wiper 1 of the stepping switch moves into engagement with terminal 2 of the switch bank A, a circuit is closed from positive terminal of battery BA, conductor 94, detonator 21, conductor 106, switch arm 107 and contact 2 of the selector switch SS, conductor 108, terminal 2 of bank A and wiper 1 of the stepping switch, conductor 102, contacts 77 of the time delay relay TD2 conductor 99, contacts 93 and thence to the negative terminal of battery BA thereby causing the detonator to.-

operate and explode the mine beneath the vessel.

Terminal 2 of level A of the switch bank, it will bel noted, is connected to terminal 3 of level B of the stepping switch as by the conductor 109 thereby providing an arrangement in which, with the selector switch SS set in position 2 as in the assumed example, if, for any reason the detonating circuit is not closed by the wiper 1 when the stepping switch is in position 2 the detonator will operate as the wipers of the switch move into position 3 in response to a subsequent operation of the firing contacts FC over the following circuit: positive terminal of battery BA, conductor 94, detonator 21, conductor 106, wiper 107 and contact 2 of switch SS, conductors 108 and 109, terminal 3 of level B and wiper 2 of the stepping switch, conductor 102, contacts 77 of the time delay relay TD2, conductor 99, contacts 93, and thence to negative terminal of battery BA. An arrangement is thus disclosed in which the detonator is operated selectively over a circuit including the wiper 1 of the stepping switch and a particular terminal thereof corresponding to the set position of the selector switch SS and, in the event that the detonator should fail to operate over this circuit for any reason such, for example, as the failure of the wiper 1 to make electrical contact with the selected terminal thereof, a circuit is closed by way of wiper 2 and the next succeeding terminal of the level B switch bank to cause the detonator to operate asfthe 9 switch is stepped ahead in response toa subsequent operation of the tiring contacts FC.

When the selector switch SS is set to position 10 theref, ten steps are required of the stepping switch to advance the wipers to their terminals 10. When this occurs the detonator 21 is operated by a circuit including terminal of switch bank A and wiper 1 of the stepping switch.

The system is also adapted to operate -the detonator in response to the first closure of the firing contacts FC, if desired, it being merely necessary to set the selector switch SS in position l with the switch wiper 107 thereof in engagement with contact 1 of the switch.

Whereas in the illustrative embodiment of the invention, the Selector and stepping switches are each shown as having an initial position and ten moved positions, it will be understood that this has been done for the purpose of illustration only and that the selector and stepping switches employed with the present invention may comprise a structure having a greater or lesser number of moved positions, if desired, without departing from the principle and the scope of the invention herein disclosed. ln the event that a switch mechanism having a greater number of moved positions is employed, it is, of course, merely necessary to connect the terminals including the added terminals of the switch SS to the switch banks A and B generally in the manner of Fig. 7. Furthermore, if desired, the switch bank B may be omitted and the firing of the mine controlled by the relative settings of the switch SS and wiper 1 of the electro-responsive stepping switch.

Briefly stated in summary the present invention provides a system for controlling the firing of a submarine mine selectively in response to a predetermined number of changes in the magnetic field adjacent thereto in which the means for detecting said changes in the m-agnetic iield are caused to be ineffective for a predetermined period of time immediately following a change in the field and in which the number of such changes required to explode the mine may be varied at will in accordance with the setting of a control element. A System is thus provided in which a predetermined number of firing impulses is required to arm the mine and in which the possibility of receiving more than one such impulse during a single passage of a mine sweeper within the vicinity of the mine is prevented and the present invention, therefore, provides .a system in which, by employing a plurality of mines set to different numbers of impulses to control the tiring thereof, a relatively large number of passages of the mine sweepers above each of the mines of the mine field is required to sweep the eld clear of mines.

It has been found advantageous in Sweeping a mine eld by electromagnetic impulses transmitted from a sweep wire attached to a moving vessel to apply the electric current to the sweep wire for relatively brief periods of time such, for example, as two or three seconds and to discontinue the flow of current through the sweep wire for susbtantially sixty seconds thereby to conserve the electric energy required to set up an effective electromagnetic iield yabout the sweep wire. More specifically, the time required for the timing mechanism TD2 to complete a cycle of operation is preferably somewhat longer than the interval of time between the two successive impulses transmitted by a sweep wire during the passage of the sweep wire above the mine and for this reason the stepping magnet SM of the electro-responsive selecting switch cannot be additionally operated for a predetermined period of time, such as 70 seconds after the iirs-t sweep impulse has been received for the reason that contacts 76 of the timing clock TD2 remain in open position until the cycle of operations of the clock has been completed. After a period of time of 70 seconds has elapsed contact 76 is in closed position thereby operatively connecting the timing clock TD1 to the tiring contacts FC l shortly after the sweep wire has passed the mine and thus the possibility of the safe passage of an enemy vessel immediately following the passage of the sweep wire past the mine is prevented.

While the invention has been described with particularity as to one preferred embodiment of a combination of mechanisms and of each of the elements of the combination, it is to be understood that this has been done for purposes of disclosure and that various changes and substitutions may be readily apparent to those skilled in the art to which the invention pertains, after understanding the invention herein disclosed, and that the terms employed in the appended claims are to be considered as Words of description rather than words of limitation.

The invention herein disclosed and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. In asubmarine mine adapted to be laid on the bed of a body of water adjacent the path of travel of a vessel, means responsive to a change in the terrestrial magnetic field adjacent the mine for closing a pair of tiring contacts in response to a change in the magnetic field, a first time delay timing device having a pair of normally closedcontacts adapted to be opened as the timing device operates, a second time delay timing device having a pair of normally open contacts adapted to be closed when the second timing device has operated for a predetermined period of time, a source of electrical power, electro-responsive means included in said second timing device adapted to be operated by said source of power as said tiring contacts are moved to closed position while the closed contacts of said rst timing device are in closed position, electro-responsive means controlled by said normally open contacts of said second timing device for causing the rst timing device to perform a cycle of operations, a pair of normally open contacts on said rst timing device adapted to be moved to closed position during said cycle of operations, an electro-responsive switching device controlled by said last named contacts having a plurality of electrical conductors connected thereto, said electro-responsive switching device including circuit closing means adapted to select different ones of said plurality of conductors in succession as the switching device operates, a detonating device, means settable at will for operatively connecting said detonating device to a predetermined one of said plurality of conductors, and means for causing said detonating device to explode the mine when the electro-responsive switching device has selected said predetermined one of said plurality of conductors.

2. In a system Vfor firing a submarine mine selectively in accordance with a predetermined number of signals received in time spaced relation, an electrical circuit, a source of power, means responsive to said signals for closing said electrical circuit from said source of power, a pair of time delay devices operable in predetermined sequential order in response to the closure of said circuit by said circuit closing means, an electro-responsive switch device having a plurality of terminals thereon and adapted to select said terminals in succession as the device operates, means controlled by said pair of time delay devices for causing said selecting mechanism to select the terminals thereof in succession, detonating means, and means settable at will for operatively connecting said detonating means to a desired one of said plurality of terminals of said switch device, and means effective when said switch device has selected a desired one of said plurality of conductors for causing the detonating means to be operated by said source of electrical power.

3. In a system of the character disclosed for controlling the tiring of a submarine mine selectively in accordance withV a predetermined number of changes in the earths magnetic field adjacent the mine, a source of power, a

pair of firing contacts adapted'to be closed in response to a change in said magnetic field, a first electro-responsive` time delay device operatively connected to said tiring contacts and adapted to be operated thereby, a second time delay device having a pair of normally closed contacts adapted to interrupt the electrical connection between the firing contacts and said first electro-responsive time delay device as the second time delay device operates, means for causing the second time delay device to disengage said normally closed contacts in response to the operation of said firstv time delay device, a stepping switch mechanism adapted to. establish an electrical connection to different ones of a plurality of conductors in predetermined successive order, means including a pair of normallyv open contacts on said second time delay device adapted to be closed as the second time delay device operates for causing the stepping switch mechanism to select said electrical conductors singly in succession, a detonating device, means settable at will for operatively connecting said detonating device to a predetermined one of said electrical conductors, means controlled by said normally closed contacts of said second time delay device for preventing the operation of said stepping mechanism in response to additional changes in said magnetic field adjacentV the mine for a predetermined period of time after the firing contacts have been closed, and means for causing said detonating device to explode the mine when said predetermined one of said conductors has been selected by said stepping switch mechanism.

4. In a system of the character disclosed for controlling the tiring of a submarine mine selectively in accordance with a predetermined number of changes in the magnetic field adjacent thereto occurring in predetermined time spaced relation, a pair of tiring contacts, a pivoted magnetic element adapted to close said firing contacts in response to a change in said magnetic field, a first time delay device adapted to be operated by said firing contacts and having a pair of normally open contacts thereon, a second time delay device adapted to perform a cycle of operations in response to the closure of the normally open contacts of said first time delay device, an electroresponsive stepping switch device having a plurality of terminals thereon adapted to be selected singly in succession as the switch device operates, a detonating device operatively connected to a predetermined one of said terminals, a source of electrical power, means for causing said detonating device to operate when said predetermined one of said terminals has been selected, a pendulum device having normally disengaged contact means adapted to be engaged as the mine is disturbed, a slow releasing relay operatively connected to said contact means and adapted to be operated as the contact means are engaged, and means controlled by said slow releasing relay for preventing the operation of said first and second time delay devices for a predetermined period of time after the pendulum contact means have been engaged.

5. In a system of the character disclosed for controlling the firing of a submarine mine, a switch stepping device having a plurality of contact elements thereon, means including a switch wiper for engaging said contact elements singly in succession as the switch operates, means including an electromagnet for moving said switch wiper into engagement with said contact elements successively, means including a restore magnet for resetting the switch wiper to an initial position, a source of electrical power, means controlled by the pressure of the water within which the mine is submerged for connecting said restore magnet to said source of electrical power thereby to reset said switch wiper to said initial position, means for disconnecting said restore magnet from said source of electrical power after said switch wiper has been reset, a control circuit, means responsive to a change in the magnetic field adjacent the mine for closing the control circuit from said source of power, a pair of time delay devices operativelyconnected to said control circuit Crt and adapted to be controlled thereby, means included in one of said time delay devices for causing said electromagnet to step the switch wipers ahead to the next succeeding contact element, detonating means, and means for causing said detonating means to operate when said switch wiper has been stepped ahead to a predetermined one of said contact elements.

6. In a system of the character disclosed for controlling the tiring of a submarine mine selectively in accordance with a predetermined number of signal indications received, a switch stepping mechanism having a plurality of electrical contacts thereon, a plurality of switch wipers adapted to engage said electrical contacts in succession as the switch operates, means including an electromagnet for causing said switch wipers to engage Said contacts in succession, signal indicating means having a pair of firing contacts adapted to be closed as the signals are detected, a timing mechanism operatively connected to said firing contacts and adapted to be controlled thereby, means included in said timing mechanism for operating said electromagnet in time delayed relation with respect to the closing of said pair of tiring contacts, detonating means, and means for causinU said detonating means to operate when Said switch wipers have engaged a predetermined number of said electrical contacts.

7. In a system of the character disclosed for controlling the ring of a submarine mine selectively in accordance with a predetermined number of signals received within the vicinity of the mine, a source of power, means responsive to said signals for closing an electrical circuit from said source of power, a slow acting device adapted to close a pair of normally open contacts in timeV delayed relation to the operation of said circuit closing means, a cycling device having electro-responsive means adapted to be operated by the normally open contacts of Said slow acting device as the normally open contacts thereof close, means included in said cycling device for releasing said slow acting device as the cycling device operates, a switch stepping mechanism controlled by said cycling device and having a plurality of sets of electrical terminals adapted to be engaged in succession by theV respective wipers thereof as the switch stepping mechanism operates, detonating means, and means for causing said detonating means to explode the mine when the wiper of each set of said switch stepping mechanism has engaged a predetermined electrical terminal thereof.

8. In a system of the character disclosed for controlling the firing of a submarine mine selectively in accordance with a predetermined number of signal indications received in time spaced relation, a pivoted magnetic element having a pair of firing contacts adapted tobe closed as the magnetic element is moved to a firing position in response to a change in said magnetic lield, a first time delay device operatively connected to said firing contacts and adapted to be set in operation as said firing contacts are closed, a second time delay device operatively connected to said first time delay device and adapted to be set in loperation thereby when a predetermined period of time has elapsed after the first time delay device has been set in operation, said second time delay device having a pair of normally closed contacts adapted to disconnect said first time delay device from the firing contacts as the second time delay device operates, a pair of normally open contacts on said second time delay device adapted to be closed for a relatively long period of time when the second time delay device has been operated, a switch stepping mechanism adapted to establish an electrical connection to a plurality of contact elements in succession, electroresponsive means controlled by said normally open contacts of the second time delay device for actuating said stepping switch mechanism as the normally open contacts are moved to closed position, a plurality of electrical conductors respectively connected to said contact eleessaies ments, detonating means, means settable at will for operatively connecting said detonating means to a predetermined one of said plurality of electrical conductors, and means for causing the mine to be exploded by said detonating means when said switch stepping mechanism has established an electrical connection to said predetermined one of said electrical conductors.

9. In a system of the character disclosed for controlling the tiring of a submarine mine selectively in accordance with a predetermined number of changes in the magnetic field adjacent thereto occurring in predetermined time spaced relation, means for detecting said changes in the magnetic field, a pair of ring contacts included in said detecting means adapted to be closed as said changes are detected thereby, means for maintaining said firing contacts in closed position, a time delay device controlled by said firing contacts having means for releasing said ring contacts when a predetermined period of time has elapsed after the lring contacts have been closed by a change in said magnetic field, a control circuit, means included in said time delay device for closing the control circuit for an additional period of time after said tiring contacts have been released, `a stepping switch device operatively connected to said control circuit and having two sets of contact elements thereon, a pair of electrically connected switch wipers adapted to engage the contact elements of each of said sets in succession as the switch device operates, detonating means, means settable at will for connecting said detonating means to a predetermined one of said contact elements of one of said sets, a branch connection from said predetermined contact element of the rst of said sets to the next succeeding contact element of the second of said sets, a source of power, and electrical conducting means operatively connected to said pair of switch wipers for causing the detonating device to be operated from said source of power in response to either of two changes in said magnetic eld detected by said detecting means.

10. In a system for controlling the ring of a submarine mine selectively in accordance with a predetermined number of signal conditions received, signal detecting means having a pair of contacts adapted to be closed as the signals are detected, a pair of timing devices controlled by said pair of contacts adapted to close a control circuit for a predetermined period of time after each signal condition has been detected, an electroresponsive stepping switch device connected to said control circuit having a plurality of electrical terminals thereon adapted to be engaged singly in succession as the switch device operates, a source of power, a detonating device adapted to be operated by said source of power, means settable at will to different settings for operatively connecting said detonating device to a selected one of said plurality of electrical terminals selectively in accordance with the setting of said settable means, and means including an electrical conducting element for causing said detonating device to be operated by said source of power when said switch stepping device has engaged a particular electrical terminal corresponding to the setting of said settable means.

11. In a system of the character disclosed for firing a submarine mine selectively in accordance with a predetermined number of changes in the magnetic eld adjacent thereto occurring in predetermined time spaced relation, an electric circuit means adapted to detect said changes in the magnetic eld and close said electric circuit as each change is detected, means including a pair of interconnected time delay devic controlled by said electric circuit and operable in a predetermined successive order for rendering said detecting means unresponsive to additional changes in said magnetic eld for a predetermined period of time after each change is detected, an explosive charge, a detonating device, and means for causing said detonating device to i'lre said explosive charge in response to a predetermined number of operations of said time delay devices.

12. In a system of the character disclosed for controlling the tiring of a submarine mine selectively in accordance with a predetermined number of signals received through the surrounding water, signal detecting means having a pair of ring contacts adapted to be closed as the signals are detected, a timing mechanism operatively connected to said firing contacts and adapted to be controlled thereby, a control circuit, means included in said timing mechanism for closing said control circuit in time delayed relation with respect to the closing of said ring contacts, a normally open firing circuit, and means operatively connected to said control circuit and adapted to close said ring circuit when said predetermined number of signals have been detected by said signal detecting means.

13. In a system for ring a marine mine selectively in accordance with the number of signals received through the surrounding water, signal receiving means within said mine, a pair of firing contacts included within said signal receiving means and adapted to be closed as the signals are received, an electro-responsive timing mechanism controlled by said pair of tiring contacts and adapted to operate in unit cycles, an electro-responsive switch device having a plurality of electrical terminals, means for engaging said terminals in succession as the switch operates, means on said timing mechanism for causing said switch device to operate in time delayed relation with respect to the closing of said iring contacts during a cycle of operations of said timing mechanism, and a ring circuit connected to a predetermined one of said terminals and adapted to be closed by said switch device when said timing mechanism has performed a predetermined number of cycles of operation.

References Cited in the file of this patent UNITED STATES PATENTS 1,310,568 Heap et al July 22, 1919 1,382,374 Maxim June 21, 1921 1,471,628 Palmer Oct. 23, 1923 1,491,004 Duie Apr. 22, 1924 FOREIGN PATENTS 803,907 France July 20, 1936 541,624 Great Britain Dec. 4, 1941 

